Is there a way to programmatically determine if a font file has a specific Unicode Glyph?

Question

I\'m working on a project that generates PDFs that can contain fairly complex math and science formulas. The text is rendered in Times New Roman, which has pretty good Unic

Answer 1

Scott's answer is good. Here is another approach that is probably faster if checking just a couple of strings per font (in our case 1 string per font). But probably slower if you are using one font to check a ton of text.

    [DllImport("gdi32.dll", EntryPoint = "CreateDC", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern IntPtr CreateDC(string lpszDriver, string lpszDeviceName, string lpszOutput, IntPtr devMode);

    [DllImport("gdi32.dll", ExactSpelling = true, SetLastError = true)]
    private static extern bool DeleteDC(IntPtr hdc);

    [DllImport("Gdi32.dll")]
    private static extern IntPtr SelectObject(IntPtr hdc, IntPtr hgdiobj);

    [DllImport("Gdi32.dll", CharSet = CharSet.Unicode)]
    private static extern int GetGlyphIndices(IntPtr hdc, [MarshalAs(UnmanagedType.LPWStr)] string lpstr, int c,
                                              Int16[] pgi, int fl);

    /// 

    /// Returns true if the passed in string can be displayed using the passed in fontname. It checks the font to 
    /// see if it has glyphs for all the chars in the string.
    /// 
    /// The name of the font to check.
    /// The text to check for glyphs of.
    /// 
    public static bool CanDisplayString(string fontName, string text)
    {
        try
        {
            IntPtr hdc = CreateDC("DISPLAY", null, null, IntPtr.Zero);
            if (hdc != IntPtr.Zero)
            {
                using (Font font = new Font(new FontFamily(fontName), 12, FontStyle.Regular, GraphicsUnit.Point))
                {
                    SelectObject(hdc, font.ToHfont());
                    int count = text.Length;
                    Int16[] rtcode = new Int16[count];
                    GetGlyphIndices(hdc, text, count, rtcode, 0xffff);
                    DeleteDC(hdc);

                    foreach (Int16 code in rtcode)
                        if (code == 0)
                            return false;
                }
            }
        }
        catch (Exception)
        {
            // nada - return true
            Trap.trap();
        }
        return true;
    }